The primary function of a chimney is to draw fire and smoke out, expel fumes, and improve combustion conditions. In high-rise buildings, various vertical shafts are typically provided, such as stairwells, ventilation shafts, air supply ducts, exhaust ducts, elevator shafts, and pipeline shafts, in varying numbers. When the indoor temperature is higher than the outdoor temperature, the warm air inside, being less dense, naturally rises through these vertical passages. It escapes through gaps in doors and windows and various openings from the upper levels. Outside cold air, being denser, seeps in from the lower levels to compensate, thus creating the chimney effect. The chimney effect is the result of the combined action of the heat pressure caused by the indoor-outdoor temperature difference and the wind pressure outside, with the former usually being predominant. The heat pressure is directly proportional to the air density difference due to the indoor-outdoor temperature difference and the height difference between the intake and exhaust openings. This indicates that the higher the indoor temperature is above the outdoor temperature and the taller the building, the more pronounced the chimney effect becomes. It also suggests that the chimney effect in residential buildings generally occurs only during winter. In terms of a single building, theoretically, the midpoint height of the building is considered the neutral zone, where rooms below the neutral zone receive air from outside, and rooms above the neutral zone expel air from inside.

Key points to note in the construction of chimney anti-corrosion:

1. Construction sites must be clean and well-ventilated, with harmful gas levels not exceeding specified requirements. Flammable materials, except for those used in the anti-corrosion painting of chimneys, are strictly prohibited from being stored on the construction site. In other words, pay attention to environmental safety and keep the site clean.

2. Smoking is prohibited on-site. Welding or open flame work is not allowed within a 10-meter radius. Explosion-proof lighting equipment must be used during construction. Workers should wear necessary protective gear, operate in containers in shifts, and ensure good ventilation. Anti-slip measures must be in place, and workers must wear safety belts.

3. Chimney anti-corrosion work is completed. When cleaning tools and containers with waste solvents, do not pour them carelessly and dispose of them properly. In case of any accidents, place them in designated areas.